No start on 13B with ITBs

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No start on 13B with ITBs

Postby hydrochloric » Sun Oct 29, 2017 5:52 pm

Hi all,

So I just finished installing an MS3X setup on my FB (13B). It was previously carby, so there was a lot of work to do to get the MS on it. It's got LS coils (running in RX8 mode), a GSX-R throttle body set with 630cc injectors, and an FC CAS.

I get good sync, good injection event, spark is good (though I did have the leading and trailing plugs reversed- oops). I set timing, but I realized now I set timing way off, because I was actually timing off the trailing plug. I'll correct that later, but here's an interesting thing- I got the car to start ONCE, with -10 of timing (so the leading plug was probably around 2*) and about 15% throttle, but it wouldn't stay running.

Ever since, I've had zero luck. I've flood cleared it 3 times, dried and heated the plugs, etc. The ECT rises as I try, so there's ignition occurring... But it's only enough to speed up the cranking, not enough to light off.

I think the main issue is the temp here is around 40F, and the manifold I built means the injectors are really just coating the walls. But starting fluid doesn't help, even.

Anyway, here's a picture of the intake setup, for an idea. I'll include the MSQ, but there's nothing to datalog, really...
Image
Image
Attachments
FB RX7 ITB.msq
(274.68 KiB) Downloaded 5 times
Last edited by hydrochloric on Mon Oct 30, 2017 3:38 pm, edited 1 time in total.
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Re: No start on 13B with ITBs

Postby elutionsdesign » Mon Oct 30, 2017 5:20 am

There is always something to datalog, often reveals why its not starting.
Graduate of EFI University.

I build, repair, install and tune Megasquirt systems in North Dakota and beyond!
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Re: No start on 13B with ITBs

Postby hydrochloric » Mon Oct 30, 2017 3:37 pm

elutionsdesign wrote:There is always something to datalog, often reveals why its not starting.


Well, here's what I got. The AFR isn't real, it's not installed yet. Thought I disabled it, but nope.

I also corrected the timing, it's dead on 0* now (at least at cranking).

As the "fresh crank" log shows, it started to speed up but then... just stops trying from there.

I then tried heating the manifold with a heatgun, to see if it would help atomize the fuel. No change.

EDIT: And I just realized I had the displacement doubled in required fuel... Quite possibly flooding before it could even try to start.
Attachments
no-start MSL.zip
Two log files in here
(30.15 KiB) Downloaded 4 times
hydrochloric
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Re: No start on 13B with ITBs

Postby hydrochloric » Wed Nov 01, 2017 4:42 pm

So I tried again today, corrected required fuel. Still nothing. At this point it MUST be flooded. I'll have to try a really in-depth deflood, oil in the spark plug holes etc... Maybe I can convince my friend with a duramax to tow it.
Attachments
2017-11-01_19.01.42.msl
(382.04 KiB) Downloaded 5 times
hydrochloric
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Re: Rough start & idle on 13B with ITBs

Postby hydrochloric » Sun Nov 19, 2017 1:28 am

Huge update! It runs! :yeah!: Kinda.

My major problem was having my fuel injector wiring swapped F/R rotors, oops. I also talked to someone who'd built an ITB 13B, and got his tune. With some tweaks, it works well for me so far. I can fairly reliably get the car started, but it's not easy. Takes a lot of throttle playing.

The next big issue is losing sync. Above ~1500 it's fine. Below that it gets very inconsistent, so the idle is... Well rough would be an understatement. Oddly there's no syncing issues when cranking at much lower speeds. I feel as though it's missing and the feedback is causing the problem, but I have no way to tell why. I did get some high speed datalogs, but they don't mean anything to me yet.

So I'll include two logs, one shows how difficult starting can be (getting it out of the first column of the VE table, ~1500RPM and its fine). The next is the idle, with the RPM dropping out. I can also include a highspeed log if needed.

Any help is greatly appreciated! Also the AFR is wrong, I discovered quite a large exhaust leak before it, so don't read into that one much.
Attachments
Idle syncing 11-18-17.msl
Idle trigger sync issues
(369.33 KiB) Downloaded 3 times
Starting 11-18-17.msl
Starting Issues
(436.71 KiB) Downloaded 4 times
FB RX7 ITB 11-18-17.msq
Tune from logs
(274.68 KiB) Downloaded 5 times
hydrochloric
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